All Fisslers have the second valve. It is automatic and can also easily be held open to release pressure for the "quick" release method by pushing a button in the handle. Steam is directed away from the handle and away from a user's hand. Another reason I like the 2nd valve is that when zero pressure has been achieved it prevents negative pressure inside when doing a running water release. It makes a very audible hissing sound as air is sucked in after pressure has been completely released. By what you are saying it sounds like the Kuhn Top model would be pretty easy to leave open for a minute or two to expel oxygen/steam right after closing the lid. It sounds like closing the valve is pretty easy too.

Money & 2nd valve aside, a major factor could influence which brand to buy. One is the physical size of the units. You say that you want a 7 or 8 liter. The 8 liter Fissler is 26 cm in diameter while the 6 liter is 22 cm in diameter. The 7 liter Kuhn is 22cm in diameter. I have a 10 liter Fissler & it is a big unit. It fits a 6 quart pot (handles removed) inside on a tripod. The only difference between it & the 8 liter version is it's height. I'd guess that the 7 liter Kuhn would be easier to handle than the 8 or 10 liter Fisslers simply because it has a smaller diameter.(and probably lower weight)

Hope I have not confused the issue. Whichever unit you purchase, I am sure you will like it. I have used pressure cookers for about 15 years and would not want to cook without one.